This invention relates to a locking device for excavating equipment and, more particularly, to a releasable lock for securing a slip-over adapter to the lip of a shovel dipper or the like.
For over a century, excavating equipment has been equipped with forward projections generally referred to as teeth to facilitate penetration of the earth being worked. For many years these were either bolted or welded onto the lip of the excavating bucket or dipper. In the early 1900's, workers in this art appreciated the need for renewing these wedge-shaped teeth and worked on a number of variations of 2-piece teeth wherein there would be a minimum amount of throw-away metal. For many years the difficulty lay in providing a suitable interlock between the two parts of the tooth--one that would hold the forwardly-extending point securely on the rearwardly-extending adapter (which in turn was attached to the excavating equipment) at times of stress, yet could be easily disassembled for replacement.
The first successful two-part tooth which was widely used throughout the world is seen in U.S. Pat. No. 2,483,032. There a notched tapered locking pin was engaged by a metal faced rubber locking plug housed within the adapter. Since that time, a great deal of attention has been focused on the locking devices which hold the point on the adapter, particularly the notch or notches that engage the resilient element. However, there has not been the same attention paid to the means for securing the adapter to the dipper, bucket, etc. Many times, workers in the art have thought that the lock between the point and adapter could be utilized (with suitable enlargement) to connect the adapter to the excavator lip. This has not proved the case because the stresses were different and the masses of material involved in the connected elements adjacent the lock were also quite different. Normally, the adapter has substantially greater mass than the point, often weighing three to four times as much.
The adapters, at their rearward ends which were secured to the excavator lip, normally partook of two basic shapes--the so-called "Whisler" adapter which had bifurcated arms so as to slip over the lip, and the shank type adapter (see U.S. Pat. No. 2,919,506) which fitted within a recess within the forward edge of the lip.
As far as the Whisler type adapter was concerned, early on the workers in this art favored a C-shaped clamping member suitably held in place by a lock--see, for example, U.S. Pat. No. 3,121,289--and it is with this general type of adapter with which the instant invention is concerned. With larger excavating machines and therefore the greater stresses encountered particularly where the Whisler-type adapter was favored, it became apparent to those in the art that better locks were required between the adapter and the excavator lip because adapters had to be replaced more often. One attempt to bring serrated surfaces, i.e., a plurality of locking surfaces, into the design of the lock is seen in U.S. Pat. No. 3,121,289. This has proved successful in some instances but not universally effective, particularly where large stresses are encountered.
Coincident with the development of the serrations pictured in the '289 patent, the art workers were concerned with various types of corrugated locks (alternatively, more notches) to secure the point to the adapter--see, for example, U.S. Pat. Nos. 2,919,506 and 3,126,654.
The concept of using the horizontal corrugations of the point locks of the '506 and '564 was attempted to be translated into use for securing adapters to excavator lips-- as in U.S. Pat. Nos. 3,572,785 and 3,722,932. However, these have not been widely used, there being the feeling that the concepts useful in releasably locking points on adapters were not suitable on the larger stress area where the adapters are releasably locked onto the excavator lips.
It was therefore surprising to discover that certain elements of a point lock--as seen in our earlier U.S. Pat. No. 4,061,432--could be used to advantage in achieving a reliable, sturdy lock for securing the adapter to the excavator lip.
According to the instant invention, a C-clamp member is employed in combination with the traditional wedge member. The wedge member is serrated for engagement with a lock element fitted within a recess in the confronting face of the C-shaped clamp member. Additionally, the C-shaped clamp member in the contronting face portion is slotted to provide opposing side walls which confine the confronting serrations of the wedge member against lateral movement and thereby stabilize the connection between the two so as to achieve an unexpectedly strong and reliable lock.